US6343002B1 - Electroconductive paste, laminated ceramic capacitor, and method for manufacturing the same - Google Patents

Electroconductive paste, laminated ceramic capacitor, and method for manufacturing the same Download PDF

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Publication number
US6343002B1
US6343002B1 US09/676,329 US67632900A US6343002B1 US 6343002 B1 US6343002 B1 US 6343002B1 US 67632900 A US67632900 A US 67632900A US 6343002 B1 US6343002 B1 US 6343002B1
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electroconductive paste
particle size
laminated
internal electrodes
laminated body
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Yasushi Shimizu
Nagato Omori
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Murata Manufacturing Co Ltd
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Murata Manufacturing Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/005—Electrodes
    • H01G4/008—Selection of materials
    • H01G4/0085—Fried electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/30—Stacked capacitors

Definitions

  • the present invention relates to an electroconductive paste containing a nickel powder which can be advantageously used to form internal electrodes of a laminated ceramic capacitor, to a laminated ceramic capacitor with internal electrodes formed by using this electroconductive paste, and to a manufacturing method therefor.
  • FIG. 1 shows a cross-sectional view of a laminated ceramic capacitor 1 to which the present invention relates.
  • a laminated ceramic capacitor 1 is composed of a laminated body 3 having ceramic layers 2 comprising plural laminated dielectric ceramic bodies, and first and second external electrodes 4 and 5 , located respectively at the two edges facing each other on this laminated body 3 .
  • First internal electrodes 6 and second internal electrodes 7 are located in an alternate arrangement inside the laminated body 3 .
  • the first internal electrodes 6 are formed along plural specific interfaces between the ceramic layers 2 with respective edges exposed at one of the edges of the laminated body 3 so that they are electrically connected with the first external electrode 4 .
  • the second internal electrodes 7 are formed along plural specific interfaces between the ceramic layers 2 with respective edges exposed at the other edge of the laminated body 3 so that they are electrically connected with the second external electrode 5 .
  • the laminated ceramic capacitor 1 is, for example, manufactured in the following manner.
  • Electroconductive paste films for the internal electrodes 6 or 7 are formed on specific green ceramic sheets by applying an electroconductive paste containing a nickel powder and an organic vehicle by a screen printing method or the like.
  • the plural green ceramic sheets including those having electroconductive paste films formed accordingly are stacked, pressed, and then cut, if necessary.
  • a raw laminated body is produced which comprises plural green laminated ceramic layers, and electroconductive paste films formed along specific interfaces between these green ceramic layers.
  • This green laminated body is then baked in a nonoxidizing atmosphere. Accordingly, the green ceramic layers as well as the electroconductive paste films are sintered. These electroconductive paste films thus form the internal electrodes 6 and 7 .
  • the external electrodes 4 and 5 are then formed on the outer surfaces of the sintered laminated body so that they are electrically connected with either the internal electrodes 6 or 7 .
  • the ceramic oxide or the organometallic compound forms a solid solution in the ceramic layers 2 during the baking step, and may result in an adverse effect to the electric properties of the baked laminated ceramic capacitor 1 .
  • An object of the present invention is, therefore, to provide an electroconductive paste which can solve such problems as mentioned above.
  • Another object of the present invention is to provide a laminated ceramic capacitor having internal electrodes formed by using the above-mentioned electroconductive paste, and a manufacturing method therefor.
  • the inventors of the present invention focused on the crystal particle sizes of nickel crystals contained in nickel powder and hypothesized that choosing a specific value for the crystal particle size in relation with the average particle size of the nickel powder would act as an effective means to restrict drastic shrinkage of the nickel powder during sintering.
  • the inventors of the present invention performed intensive research to solve the above-mentioned problems and discovered a phenomenon that as the crystal particle size of a nickel crystal becomes smaller compared with the average particle size of the nickel powder, shrinkage of the nickel powder during sintering occurs more uniformly and is thus less liable to cause drastic shrinkage during sintering as compared with a case in which a crystal having a larger crystal particle size is used. The present invention has thus been achieved.
  • an electroconductive paste according to the present invention has a nickel powder dispersed in an organic vehicle, wherein the nickel powder has an average particle size of about 0.5 ⁇ m or less, and the crystal particle size of nickel crystals contained in each particle of the nickel powder is less than about 20% of the average particle size.
  • the invention is also directed to a laminated ceramic capacitor having a laminated body comprising plural laminated ceramic layers and internal electrodes located along specific interfaces between these ceramic layers, wherein the internal electrodes are obtained by baking the above-described electroconductive paste.
  • the invention is also directed to a method for manufacturing a laminated ceramic capacitor.
  • a raw laminated body comprising plural green laminated ceramic layers, and electroconductive paste films formed along the specific interfaces between the raw ceramic layers by using the above-described electroconductive paste is prepared, the raw ceramic layers are sintered by baking the green laminated body, the electroconductive paste films are sintered at the same time to form internal electrodes for a sintered laminated body, and external electrodes are formed on the outer surfaces of the sintered laminated body so that they are electrically connected with the internal electrodes.
  • FIG. 1 is a cross-sectional view illustrating a laminated ceramic capacitor which is of interest to the present invention.
  • FIG. 2 is an enlarged cross-sectional view illustrating a particle of nickel powder 8 contained in the electroconductive paste according to the present invention.
  • An electroconductive paste according to the present invention for example, has a nickel powder dispersed in an organic vehicle comprising an organic binder, an organic solvent, etc.
  • FIG. 1 illustrates a particle of nickel powder 8 chosen arbitrarily from such an electroconductive paste.
  • the particle of nickel powder 8 contains nickel crystals 9 .
  • the average particle size of the particles of nickel powder 8 is represented by D
  • the crystal particle size for each nickel crystal 9 is represented by dc.
  • the present invention is characterized in that the average particle size D for the particle of nickel powder 8 is about 0.5 ⁇ m or less, and the crystal particle size dc for the nickel crystal 9 is less than about 20% of the above-mentioned average particle size D.
  • Such an electroconductive paste is advantageously used for forming the internal electrodes 6 and 7 in the laminated ceramic capacitor 1 shown in the above-mentioned FIG. 2 .
  • the structure of the laminated ceramic capacitor 1 is the same as described in the above-mentioned explanation.
  • the method for manufacturing the laminated ceramic capacitor 1 is also substantially the same as the above-described conventional manufacturing method except that an electroconductive paste having characteristics described above is used as the electroconductive paste for use in forming the internal electrodes 6 and 7 .
  • a green laminated body comprising plural green laminated ceramic layers for forming the ceramic layers 2 is prepared, and electroconductive paste films formed along specific interfaces between the raw ceramic layers by using an electroconductive paste, the green ceramic layers are sintered by baking the green laminated body, the electroconductive paste films are sintered at the same time to form the internal electrodes 6 and 7 for the sintered laminated body 3 , and the external electrodes 4 and 5 are formed on the outer surfaces of the sintered laminated body 3 so that they are electrically connected with the internal electrodes 6 and 7 .
  • the laminated ceramic capacitor is thus completed.
  • green ceramic sheets with the electroconductive paste films formed thereon were laminated to obtain the above-described green laminated body. It is also possible to repeat application of a ceramic slurry for forming a green ceramic layer, and application of an electroconductive paste for forming an electroconductive paste film. Furthermore, an electroconductive paste film may be formed by applying an electroconductive paste on green ceramic sheets during the lamination work of the sheets.
  • a ceramic material having BaTiO 3 as a major component, an organic binder, an organic solvent, a plasticizer and a dispersant were mixed at a specified ratio, and the mixture was subjected to a wet type dispersion treatment with a ball mill to obtain a ceramic slurry. Then the ceramic slurry was applied onto a PET (polyethylene terephthalate) film by a doctor blade process to form a green ceramic sheet having a thickness of 9.0 ⁇ m after drying.
  • an electroconductive paste was applied onto the above-described green ceramic sheets by a screen printing method to form electroconductive paste films for internal electrodes so that they had a pattern which allowed a chip-shaped laminated body obtained afterward to have a flat surface having dimensions of 3.2 mm ⁇ 1.6 mm after cutting and baking, and so that they had thicknesses of 1.8 ⁇ m, 2.5 ⁇ m, and 3.0 ⁇ m after drying.
  • the above-mentioned electroconductive paste contained 50% by weight of a nickel powder, 40% by weight of an organic vehicle, a resinous solution obtained by dissolving 10% by weight of an organic binder in an organic solvent, and the balance being composed of a dispersant, a thickener, etc.
  • nickel powders in total were independently used, that is, two kinds each having an average particle size of 0.5 ⁇ m with a crystal particle size of 200 nm or 80 nm, two kinds each having an average particle size of 0.2 ⁇ m with a crystal particle size of 100 nm or 30 nm, and the other two kinds each having an average particle size of 0.1 ⁇ m with a crystal particle size of 50 nm or 15 nm.
  • the above-mentioned average particle size was obtained by taking a photograph of a nickel powder with a scanning electron microscope, subjecting the powder image to processing in an image processor, calculating circle-equivalent diameters, and then calculating an arithmetic mean value thereof.
  • the crystal particle size was calculated by the Hall method from the diffraction peaks of nickel obtained from the X-ray diffraction of a nickel powder.
  • the green ceramic sheets with electroconductive paste films printed on as described above were peeled off the PET film. Two hundred of these green ceramic sheets were stacked, placed in a mold, and were pressed. The pressed laminated body block was then cut into a specified size to produce green laminated bodies in the shape of chips for laminated ceramic capacitors.
  • Table 1 shown below indicates the number of laminated bodies having such structural defects in relation to the average particle size D of a nickel powder used for an electroconductive paste, the crystal particle size dc of the nickel crystal, the ratio dc/D of the crystal particle size dc to the average particle size D, and the thickness of the electroconductive paste film after drying and before baking.
  • the sintering initiation temperature in the baking of a nickel powder tends to be lower compared with the case in which the crystal particle size dc is larger.
  • the temperature thus lowered makes it more difficult to cause drastic shrinkage during sintering.
  • shrinkage at sintering is made difficult until the temperature is raised to a higher range. Since the diffusion coefficient becomes larger as the temperature is raised to such a higher range, the shrinkage rate during sintering becomes larger in a higher temperature range.
  • the electroconductive paste described in the present invention employing a nickel powder with the ratio dc/D of the crystal particle size dc to the average particle size D which is less than about 0.2, with the average particle size D of the nickel powder being about 0.5 ⁇ m or less, can provide a uniform shrinkage of a nickel powder at sintering during the temperature increase in the baking step, with the result that a structural defect that may occur during the baking step can be restricted.
  • the nickel powder has an average particle size of about 0.5 ⁇ m or less, and the crystal particle size of a nickel crystal contained in each particle of the nickel powder is less than about 20% of the average particle size. Shrinkage during sintering of a nickel powder thus can be generated uniformly during the temperature increase in the baking step as is clearly shown from the above-mentioned experimental results, making it less liable to shrink drastically during sintering.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Conductive Materials (AREA)
  • Ceramic Capacitors (AREA)
  • Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
  • Paints Or Removers (AREA)
US09/676,329 1999-09-30 2000-09-29 Electroconductive paste, laminated ceramic capacitor, and method for manufacturing the same Expired - Lifetime US6343002B1 (en)

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JP11-278558 1999-09-30
JP27855899A JP2001101926A (ja) 1999-09-30 1999-09-30 導電性ペースト、ならびに積層セラミックコンデンサおよびその製造方法

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JP (1) JP2001101926A (ja)
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CN (1) CN1300084A (ja)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6517745B2 (en) * 2000-02-28 2003-02-11 Mitsui Mining And Smelting Co., Ltd. Nickel powder and conductive paste
US20140049875A1 (en) * 2012-08-16 2014-02-20 Samsung Electro-Mechanics Co., Ltd. Nickel powder for internal electrode, method of producing the same, and multilayer ceramic electronic component including the same
CN108602129A (zh) * 2016-03-18 2018-09-28 住友金属矿山株式会社 镍粉、镍粉的制造方法以及使用镍粉的内部电极膏和电子部件

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3722282B2 (ja) * 2001-08-21 2005-11-30 Ｔｄｋ株式会社 金属粒子含有組成物、導電ペースト及びその製造方法
KR20210084536A (ko) 2018-10-31 2021-07-07 쇼에이 가가쿠 가부시키가이샤 Ni 페이스트 및 적층 세라믹 콘덴서

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4725573A (en) * 1983-12-31 1988-02-16 Veg-Gasinstituut, N.V. Copper-nickel catalyst and process for its production
US5536594A (en) * 1993-08-26 1996-07-16 Programme 3 Patent Holdings Electrochemical cell
JPH08246001A (ja) 1995-03-10 1996-09-24 Kawasaki Steel Corp 積層セラミックコンデンサー用ニッケル超微粉
US5600533A (en) * 1994-06-23 1997-02-04 Murata Manufacturing Co., Ltd. Multilayer ceramic capacitor having an anti-reducing agent
US5853451A (en) * 1990-06-12 1998-12-29 Kawasaki Steel Corporation Ultrafine spherical nickel powder for use as an electrode of laminated ceramic capacitors
US5910881A (en) * 1996-06-14 1999-06-08 Murata Manufacturing Co., Ltd. Multilayered electronic element
US6074785A (en) * 1997-04-14 2000-06-13 Matsushita Electric Industrial Co., Ltd. Nickel/metal hydride storage battery
US6118648A (en) * 1997-03-31 2000-09-12 Tdk Corporation Non-reducing dielectric ceramic materials

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4725573A (en) * 1983-12-31 1988-02-16 Veg-Gasinstituut, N.V. Copper-nickel catalyst and process for its production
US5853451A (en) * 1990-06-12 1998-12-29 Kawasaki Steel Corporation Ultrafine spherical nickel powder for use as an electrode of laminated ceramic capacitors
US5536594A (en) * 1993-08-26 1996-07-16 Programme 3 Patent Holdings Electrochemical cell
US5600533A (en) * 1994-06-23 1997-02-04 Murata Manufacturing Co., Ltd. Multilayer ceramic capacitor having an anti-reducing agent
US6143109A (en) * 1994-06-23 2000-11-07 Murata Manufacturing Co., Ltd. Multilayer ceramic capacitor and process for producing the same
JPH08246001A (ja) 1995-03-10 1996-09-24 Kawasaki Steel Corp 積層セラミックコンデンサー用ニッケル超微粉
US5910881A (en) * 1996-06-14 1999-06-08 Murata Manufacturing Co., Ltd. Multilayered electronic element
US6118648A (en) * 1997-03-31 2000-09-12 Tdk Corporation Non-reducing dielectric ceramic materials
US6074785A (en) * 1997-04-14 2000-06-13 Matsushita Electric Industrial Co., Ltd. Nickel/metal hydride storage battery

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6517745B2 (en) * 2000-02-28 2003-02-11 Mitsui Mining And Smelting Co., Ltd. Nickel powder and conductive paste
US20140049875A1 (en) * 2012-08-16 2014-02-20 Samsung Electro-Mechanics Co., Ltd. Nickel powder for internal electrode, method of producing the same, and multilayer ceramic electronic component including the same
CN108602129A (zh) * 2016-03-18 2018-09-28 住友金属矿山株式会社 镍粉、镍粉的制造方法以及使用镍粉的内部电极膏和电子部件
US11376658B2 (en) * 2016-03-18 2022-07-05 Sumitomo Metal Mining Co., Ltd. Nickel powder, method for manufacturing nickel powder, internal electrode paste using nickel powder, and electronic component
CN108602129B (zh) * 2016-03-18 2022-08-23 住友金属矿山株式会社 镍粉、镍粉的制造方法以及使用镍粉的内部电极膏和电子部件
US11772160B2 (en) 2016-03-18 2023-10-03 Sumitomo Metal Mining Co., Ltd. Nickel powder, method for manufacturing nickel powder, internal electrode paste using nickel powder, and electronic component

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CN1300084A (zh) 2001-06-20
KR20010030501A (ko) 2001-04-16
KR100379205B1 (ko) 2003-04-08
JP2001101926A (ja) 2001-04-13

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